Add configurable timeout for path encryption/decryption with gocryptfs-xray

[Dekedro]

For virtual filesystems (e.g. filesystem over network) operations can take more than 1 second (which is current timeout value). It would be useful to be able to control timeout duration (or make it infinite) via some CLI flag.

[rfjakob]

Agreed, raised the timeout to 10 seconds. Hope that's enough.